Tesis
Determinação de resíduos de agrotóxicos em mel empregando método QuEChERS modificado e GC-ECD
Fecha
2011-08-03Registro en:
ORSO, Débora. Determination of pesticide residues in honey by modified QuEChERS method and GC-ECD. 2011. 118 f. Dissertação (Mestrado em Química) - Universidade Federal de Santa Maria, Santa Maria, 2011.
Autor
Orso, Débora
Institución
Resumen
The production of honey has been increasing continuously in the world in function of
the greatest consume of natural products. It is related directly to human health, and stimulated
by its therapeutics and nutritious qualities. Due to this, it is necessary the verification of the
features related to honey quality as: physical-chemical characteristics and identification of the
floral and geographic origin of this product. For such intention emerges the importance of the
residues analysis and monitoring to ensure its supply.
In this study was developed and validated a method for the determination of 23
pesticide residues in honey using modified QuEChERS method and Gas Chromatography
with Electron Capture Detection (GC-ECD). The fortification of honey samples was
preformed, with a solution containing the 23 pesticides, in 3 levels of concentration (10.0;
20.0 and 50.0 μg kg-1), 6 extractions of each level was realized, and the modified QuEChERS
method was applied. This extraction method consisted to weight 2.5 g of honey and the
addiction of 5 mL of a Na2EDTA solution 0.1 mol L-1 and 5 mL of acetonitrile followed by
vortex shaking, for 3 min. Partition consisted of the addiction of 6.0 g of anhydrous
magnesium sulfate and 1.5 g of sodium chloride shaked for 1 min, followed by centrifugation
for 8 min. The purification of the extract was realized through a dispersive clean up step in
which 2 mL of the extract was transferred to another tube, previously added 120 mg
anhydrous magnesium sulfate and 100 mg of primary secondary amine (PSA) followed by
vortex shaking and centrifugation. Finally the extracts were analyzed by GC-ECD.
The linearity of the analytical curves (6 levels of concentration and 6 injections of
each level), detection limit (LOD), quantification limit (LOQ), matrix effects, accuracy and
precision of the analytical method were evaluated. In general the linear range of the analytical
curves prepared in acetonitrile and matrix matched were between 5.0 or 10.0 to 100 μg L-1
with values of r2 > 0.99. The GC-ECD technique enables the quantification of 95.6% of the
compounds and method LOQ of 3.0 or 6.0 μg kg-1. Therefore, the method proved
appropriated for pesticide multiresidue determination in honey, as well, effective purification
technique for honey extracts combining good sensitivity and selectivity. All the parameters
evaluated are in agreement to limits suggested for chromatographic methods validation.